By the way, almost all canned pumpkin is really butternut squash, not the big orange pumpkins used to make jack-o-lanterns. Pay no attention to the picture on the can's label!
No, it's not deceptive labeling. The term "pumpkin" is ill-defined and can be applied to pretty much any suitable winter squash variety. Whether or not a given variety of winter squash is called a "pumpkin" or a "squash" is strictly a matter of outer appearance.
In fact, what we call a butternut squash in the US is called a butternut pumpkin in Australia.